Centrifugal extractors such as those used in washing machines to spin dry a load of clothes having been washed and rinsed incorporate upwardly opening tubs into which clothes to be washed may be placed and the tubs are mounted for rotation about the center axes of the tubs by journal structure including resilient components enabling the center axes and the tubs to gyrate about center positions of those axes responsive to dynamic imbalance of the tubs. Washing machine spin dry tubs of this type are capable of operating effectively and without damage thereto under slight to medium dynamic imbalance conditions, but the dynamic imbalance of such tubs can be excessive when larger items such as sheets and bedspreads are being washed.
Excessive dynamic imbalance of washing machine tubs causes the outer peripheral portions of the tubs to strike stationary components of the washing machine during rotation of the tubs at spin-drying speeds and contact between the tubs and stationary washing machine components not only causes damage to those components engaging each other, but may also cause the entire washing machine to "walk" over the floor and water connections between stationary water supply pipes and the washing machine to be broken.
Accordingly, a need exists for structure by which dynamic imbalance of a rotating washing machine spin-drying tub or similar structure may be effectively reduced.
Various different forms of rotating drum or tub balancing structures including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 2,463,801, 2,538,246, 2,886,979, 3,060,713 and 3,066,522 as well as Great Britain Pat. No. 663,829 and German Pat. No. 1,214,613.